Time-resolved in-situ dislocation density evolution during martensitic transformation by high-energy-XRD experiments: A study of C content and cooling rate effects

Recent studies on the mechanical behavior of martensitic steels show importance considering lath martensite as a “polycrystalline aggregate” with large distribution local yield strength. The latter depends microstructural features, such sizes, carbon (in solid solution, segregated to defects, in carbides) and density defects Internal stresses have be considered an additional contribution strength participating enlarge flow at microstructure scale. This study focuses one these dislocation density. Its evolution is followed situ upon transformation by High Energy X-Ray Diffraction experiments synchrotron beamline. A previously introduced method, based modified Williamson-Hall (mWH) analysis, improved order take account lattice tetragonality when applying mWH method. influence steel content (0.11, 0.21 0.31 wt.% C steels) cooling rate (-10, -50, -100 °C/s water-quench) during established. effect low between -10 °C/s, but becomes visible after water-quench. higher content, densities end transformation. also wider and, therefore,